An example shutter mechanism is an opening/closing device disclosed in Patent Literature 1. The opening/closing apparatus includes two linkage members composed of thin metal plates. One end of each linkage member has a through-hole through which the external thread of a fixing bolt passes. The linkage members are fixed to a slidable chassis such that the linkage members are rotatable around their one end. The other ends of the two linkage members are rotatably and slidably connected to each other such that the linkage members shift in the longitudinal direction relative to each other. A spring is stretched between the other ends of the linkage members. The spring biases the two linkage members to bring the other ends of the linkage members close to each other.
In the opening/closing apparatus, the external treads of the fixing bolts shift through the respective slide holes in the slidable chassis, the linkage members rotate relative to the slidable chassis around their one end, and the other ends of the linkage members rotate and slide, to slide the slidable chassis relative to the front panel having an opening.